WO2013043124A1 - Filtre multicouche - Google Patents

Filtre multicouche Download PDF

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Publication number
WO2013043124A1
WO2013043124A1 PCT/SG2012/000343 SG2012000343W WO2013043124A1 WO 2013043124 A1 WO2013043124 A1 WO 2013043124A1 SG 2012000343 W SG2012000343 W SG 2012000343W WO 2013043124 A1 WO2013043124 A1 WO 2013043124A1
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WIPO (PCT)
Prior art keywords
layer
openings
configuration
size
multilayer filter
Prior art date
Application number
PCT/SG2012/000343
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English (en)
Inventor
Majid EBRAHIMI WARKIANI
Haiqing Gong
Original Assignee
Nanyang Technological University
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Filing date
Publication date
Application filed by Nanyang Technological University filed Critical Nanyang Technological University
Priority to US14/346,392 priority Critical patent/US9327217B2/en
Publication of WO2013043124A1 publication Critical patent/WO2013043124A1/fr

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D29/00—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor
    • B01D29/01—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor with flat filtering elements
    • B01D29/05—Filters with filtering elements stationary during filtration, e.g. pressure or suction filters, not covered by groups B01D24/00 - B01D27/00; Filtering elements therefor with flat filtering elements supported
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D67/00—Processes specially adapted for manufacturing semi-permeable membranes for separation processes or apparatus
    • B01D67/0002—Organic membrane manufacture
    • B01D67/0023—Organic membrane manufacture by inducing porosity into non porous precursor membranes
    • B01D67/0032—Organic membrane manufacture by inducing porosity into non porous precursor membranes by elimination of segments of the precursor, e.g. nucleation-track membranes, lithography or laser methods
    • B01D67/0034—Organic membrane manufacture by inducing porosity into non porous precursor membranes by elimination of segments of the precursor, e.g. nucleation-track membranes, lithography or laser methods by micromachining techniques, e.g. using masking and etching steps, photolithography
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D39/00—Filtering material for liquid or gaseous fluids
    • B01D39/08—Filter cloth, i.e. woven, knitted or interlaced material
    • B01D39/083—Filter cloth, i.e. woven, knitted or interlaced material of organic material
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D46/00—Filters or filtering processes specially modified for separating dispersed particles from gases or vapours
    • B01D46/10—Particle separators, e.g. dust precipitators, using filter plates, sheets or pads having plane surfaces
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D67/00—Processes specially adapted for manufacturing semi-permeable membranes for separation processes or apparatus
    • B01D67/0039—Inorganic membrane manufacture
    • B01D67/0053—Inorganic membrane manufacture by inducing porosity into non porous precursor membranes
    • B01D67/006—Inorganic membrane manufacture by inducing porosity into non porous precursor membranes by elimination of segments of the precursor, e.g. nucleation-track membranes, lithography or laser methods
    • B01D67/0062—Inorganic membrane manufacture by inducing porosity into non porous precursor membranes by elimination of segments of the precursor, e.g. nucleation-track membranes, lithography or laser methods by micromachining techniques, e.g. using masking and etching steps, photolithography
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2239/00—Aspects relating to filtering material for liquid or gaseous fluids
    • B01D2239/06—Filter cloth, e.g. knitted, woven non-woven; self-supported material
    • B01D2239/065—More than one layer present in the filtering material
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2239/00—Aspects relating to filtering material for liquid or gaseous fluids
    • B01D2239/12—Special parameters characterising the filtering material
    • B01D2239/1216—Pore size
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2325/00—Details relating to properties of membranes
    • B01D2325/02—Details relating to pores or porosity of the membranes
    • B01D2325/021—Pore shapes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T29/00—Metal working
    • Y10T29/49—Method of mechanical manufacture
    • Y10T29/49826—Assembling or joining

Definitions

  • the present invention relates to a multilayer filter and methods for fabricating and preparing the same.
  • the filter device is for separation of particles from either fluid or gas.
  • the filter can be used for, but not limited to applications like isolation of waterborne pathogens, blood filtration, cell harvesting, and removal of unwanted particles from other food and industrial fluid made of liquid, gas (air) or a mixture of liquid and gas.
  • filtration is often used to concentrate small particles (e.g. microbial cells) suspended in minute concentration in fluids or gases.
  • small particles e.g. microbial cells
  • filtration-based particle concentration techniques have been used to isolate and recover waterborne pathogens into small volume for downstream analysis.
  • isolated/recovered microorganisms are more readily accessible to different detection methods using fluorescent probes.
  • Cryptosporidium parvum oocyst is a parasite commonly found in surface waters such as lakes and rivers, especially when the water is in contact with animal wastes and sewage.
  • Negative features of commercial filters like rough surface, tortuous pore path, low pore density and high coefficient of variation [4] (CV > 20%) are the major factors which compromise their efficiency and throughput during microfiltration.
  • the best homogeneity in terms of pore size distribution and pore shape in commercial membranes is possessed by the track-etched polymeric membranes (normally polycarbonate) by cylindrical pores, but the irregular array of pores on the surface, low porosity and also their angle with the surface limits the strength, flow rate and reliability of them in repeated process-scale. Therefore, these filters are normally employed in single-use laboratory analysis [3,5].
  • the invention relates to a multilayer filter.
  • the filter may be a polymeric micro/nano-filter, including micro/nano-scale precision-shaped pores (e.g. slotted shape) suitable for a wide variety of applications, and a support layer that includes a precision-shaped porous support for the membrane; the invention also relates to methods of fabricating and preparing the multilayer filter.
  • the invention provides a multilayer filter comprising at least a first layer comprising a plurality of openings and at least a second permeable layer overlaying the first layer and reducing the size of the openings.
  • the invention relates to a method of preparing a filter comprising the steps of:
  • the configuration of the second layer partitions the openings (of the first layer), thereby reducing the size of the openings.
  • Figure 1 is a cut-view of the multilayer micro-fabricated membrane embodying the present invention.
  • Figure 2 is a top-view of the multilayer micro-fabricated membrane, which shows the critical dimensions.
  • Figure 3 depicts the cross-sectional (a.1 to i.1 ) and 3-D (a.2 to i.2) schematic diagrams of the fabrication process.
  • Figure 4 shows an SEM image of a multilayer micro-fabricated membrane with square shape integrated back-support. Close-up view shows the perforated membrane.
  • Figure 5 illustrates an optical image of a multilayer polymeric membrane.
  • Figure 6 is a back-side view of a micro-fabricated multilayer membrane with slotted openings (3x 1 2 ⁇ ) and integrated support mesh.
  • Figure 7 shows the pore size distribution of a multilayer membrane with 3x 1 2 m slotted pores.
  • Figure 8 shows a schematic representation of the dead-end filtration mechanism. (This is used in our microfiltration tests).
  • Figure 9 represents the schematic of the experimental setup used for the experiments.
  • Figure 10 shows a microscopic image of part of the polymeric micro-fabricated membrane after filtration with trapped oocysts on the membrane surface.
  • Figure 11 depicts the filtration throughput of the micro-fabricated filter versus track-etched membrane for filtration of tap water at a pressure of 1 bar and turbidity of 0.5 NTU.
  • Figure 12 (a) shows various shapes of pore openings having low aspect-ratio.
  • Figure 12 (b) shows various shapes of pore openings having high aspect-ratio.
  • Figure 13(a) shows various shapes of particles having low aspect-ratio.
  • Figure 13 (b) shows various shapes of particles having high aspect-ratio.
  • Figure 14 shows schematics of blocking particles of various shapes on pore openings of various shapes.
  • the multilayer filter comprises at least a first layer comprising a plurality of openings and at least a second permeable layer overlaying the first layer and reducing the size of the openings.
  • the overlaying second layer comprises a configuration partitioning substantially every individual opening to reduce its size.
  • the multilayer filter may further comprise one or more successive layers overlaying the second layer, wherein each layer further successively reduces the size of the openings.
  • opening(s) may be used interchangeably with the term pore(s).
  • the current filter comprises several layers which at least one or two of them forms the membrane and at least one or two of them forms the support structure to reinforce the membrane.
  • the openings may be of any suitable shape.
  • the openings may be quadrilateral or oval shaped.
  • the openings may be rectangles or squares.
  • the openings may be substantially uniform in size and arranged in a substantially regular array.
  • the configuration of the second layer comprises an array of strips partitioning the openings.
  • the openings of the filter may be of any suitable size.
  • the largest dimension of an opening may be ⁇ 500 ⁇ .
  • the largest dimension of an opening may be from ⁇ 10 nm to ⁇ 500 ⁇ .
  • the filter membrane of the present invention has slotted pores (rectangular shape) with different width (i.e. 10 nm to 50 ⁇ ) depending on the width of strips on the second layer.
  • the length of the rectangular pore can also be varied from 50 nm to 200 ⁇ .
  • the exact pore size also depends on the desired application. For example, a filter membrane having a pore size equal to 0.45 Mm would be suitable for filtering bacteria such as E. coli, as well as other matters of similar size, from liquid. Pore size of around 3 m is also ideal to remove dangerous protozoa such as C. parvum oocysts from drinking water or can be used for diagnostic and microscopic applications.
  • the largest dimension of an opening is less than or equal to half the thickness of the multilayer filter.
  • each layer of the multilayer filter may be independently polymeric, metallic, silicon or a gel.
  • the filter may further comprise at least one supporting permeable layer.
  • the supporting permeable layer may comprise a grid structure.
  • the supporting permeable layer may comprise silicon, plastics or metal.
  • the layers of the multilayer filter are coherent.
  • the layers including the supporting permeable layers are coherent.
  • coherent is given its ordinary meaning of "logically or aesthetically ordered or integrated".
  • the invention also includes a method for fabricating a multilayer filter according to any aspect of the invention as described herein.
  • the method comprises the steps of:
  • step (ii) comprises depositing a first photoresist layer onto the sacrificial layer.
  • the first photoresist layer may then be contacted with a mask comprising a pattern of a plurality of openings to be copied to the first photoresist layer; exposing the masked first photoresist layer to a suitable light source.
  • the first photoresist layer may be contacted with a mask comprising a pattern of a plurality of openings to be copied to the first photoresist layer and performing photolithography to form a plurality of openings on the first photoresist layer.
  • Step A(iv) or B(iv) may comprise depositing at least a second photoresist layer onto the first layer.
  • the second photoresist layer may be contacted with a mask comprising a pattern of a configuration to be copied to the second photoresist layer and exposing the masked second photoresist layer to a suitable light source or alternatively, for step B(v), the second photoresist layer may be contacted with a mask comprising a pattern of a configuration to be copied to the photoresist layer and performing photolithography to form a configuration on the second photoresist layer; wherein the configuration of the second layer reduces the size of the opening of the first layer.
  • step A(v) further comprises removing the exposed regions of the first and second photoresist layers to form the configuration in the second photoresist layer and the openings in the first photoresist layer, wherein the configuration of the second layer reduces the size of the openings of the first layer.
  • the configuration of the second layer partitions substantially every individual opening to reduce its size.
  • any suitable photoresist may be used for fabricating the filter.
  • SU- 8 (MicroChem Corp., Newton, MA) may be used for fabricating the filter.
  • SU-8 is an epoxy-type photoresist [1 1].
  • Other examples of negative photoresist such as Polyimide, PMMA, PMGI and etc. may also be employed.
  • the sacrificial layer may comprise a dissolvable material.
  • the invention relates to a method of preparing a filter comprising the steps of:
  • fabricating at least a separate second permeable layer comprising a configuration comprising a configuration
  • positioning the second layer to overlay the first layer wherein the configuration of the second layer reduces the size of the openings.
  • the method according to any aspect of the invention may further comprise fabricating one or more successive permeable layers overlaying the second layer, wherein each layer further successively reduces the size of the openings.
  • the method fabricates the largest dimension of an opening to less than or equal to half of the thickness of the multilayer filter.
  • the method according to any aspect of the invention may also further comprise fabricating at least one supporting permeable layer over the multilayer filter.
  • the support layer is thicker than the membrane layer between 2 to 100 times.
  • the support layer can be made from another type of negative photoresist (other than SU-8, like Polyimide) with precision shape openings or even Silicon as well as PMMA and Polycarbonate (PC).
  • SU-8 negative photoresist
  • PC Polycarbonate
  • a wide variety of support structures may be employed in the present invention to support the multilayer micro-fabricated membrane.
  • the material of the support layer and membrane may be photosensitive (or photoimageable) and also suitable for radiation-based processes such as X- ray, UV, E-beam, photon beam and laser ablation.
  • radiation-based processes such as X- ray, UV, E-beam, photon beam and laser ablation.
  • the support with anisotropic/isotropic etching of Si or even prepare from PMMA or PC by laser cutting method, which will be described in great detail later.
  • the filter according to any aspect of the invention is for separating particles from a fluid.
  • Filtration with slotted membrane offers some interesting advantages over conventional filtration with circular pores.
  • the initial rate of flux decline is slower for the membrane with slotted pores compared to the membrane with circular pores since the initial particle deposition only covers a small fraction of the pores.
  • the membrane resistance during filtration is also much lower for the slotted pores compared to the circular pores.
  • the porosity of the membrane may be selected according to the intended application. In accordance with the present invention, the porosity of the membrane may be substantially higher than that found in the aforementioned methods since membrane has slotted pores and therefore pore density can be as high as 40 to 50%.
  • the same multilayer method to reduce the pore size can be used with other patterning techniques such as eiectron-beam lithography, x-ray lithography, transfer of pattern by stamping, nano-imprint lithography, inkjet or extrusion dispensing of materials to form a pattern, etc., which allows some of the techniques to generate smaller openings beyond their respective processing limits of these techniques when making the opening in a single layer of material.
  • patterning techniques such as eiectron-beam lithography, x-ray lithography, transfer of pattern by stamping, nano-imprint lithography, inkjet or extrusion dispensing of materials to form a pattern, etc.
  • FIG 1 shows a cut-view of multilayer polymeric membrane schematically, generally at 16, embodying the present invention.
  • micro/nano-filter membrane includes at least a filter layer that comprises an array of mono-sized pores, and a support layer that includes a precision-shaped support structure (Figure 2).
  • Figure 3 also shows the schematic cross-sectional (a.1 to i.1 ) and 3-D (a.2 to i.2) view of the fabrication process in details.
  • the filter membrane as shown in Figure 2 is not to scale.
  • the support layer could have a thickness in order of membrane thickness, more typically the filter layer will be substantially thinner than the support structure.
  • the filter layer thickness can be between 0.05-500 ⁇ while the support structure has the thickness of around 0.1 ⁇ -5 mm.
  • the thickness of both the membrane and the support structure can be varied, depending on the desired pore size, pore shape, porosity and filter strength.
  • One filter design for capturing C. parvum oocysts has the thickness of around 40 ⁇ (i.e. both membrane and support) and pore size of 3x12 ⁇ .
  • SU-8 2010 and SU-8 2015 were used for the development of multilayer polymeric membrane.
  • the method is described with reference to Figure 3.
  • a silicon substrate 1 ⁇ 100>, p-type, was cleaned in piranha solution (96% H 2 SO 4 and 30% H 2 O 2 ) for 25 minutes at 120°C to remove any organic contaminations on the wafer surface.
  • the substrate 1 was submerged in the buffered oxide etchant (BOE) for 3 minutes to clean the natural oxide layer. This step has a significant impact on the adhesion of the sacrificial layer to the substrate.
  • BOE buffered oxide etchant
  • the dehydration bake step was performed in Suss machine (Delta 150 VPO) for 2 minutes.
  • a thin layer of positive photoresist (sacrificial layer) 2 (AZ6220) was spin-coated on the silicon wafer 1 and cured on a hot plate at 100°C for 10 minutes ( Figure 3, a.1 and a.2). After curing the sacrificial layer 2 (i.e.
  • a thin layer of SU-8 photoresist 3 (SU-8 2010) was spin-coated on the top of the cured sacrificial layer 2 ( Figure 3, b.1 and b.2).
  • the photoresist was poured onto the substrate directly from a bottle with a large aperture.
  • any dissolvable polymer or metal i.e. with an appropriate solvent or etchant
  • PMMA Polyamide
  • Copper Copper
  • Gold Aluminium
  • a chrome coated glass mask 4 with rectangular features was used to transfer the patterns into the SU-8 photoresist 3.
  • the pitch size in the first mask 4 can be varied for different applications based on the desired porosity (f and e parameters in Figure 2). It is clear that by increasing the pitch size (i.e. pores distance in the x and y directions) the membrane porosity will be decreased.
  • UV-Lithography was carried out by Karl Suss MA6 mask aligner (Karl Suss Inc.) in the vacuum contact mode between the silicon wafer and the mask at 365 nm wavelength. Then SU-8 resist 3 was kept again on the hot plate for around 3 minutes for post-exposure at 95 °C and cooled down to the room temperature for relaxation purpose for 10 minutes. In this step, the cationic photo- polymerization of the epoxy is performed. As shown in ( Figure 3, c.1 and c.2), those exposed areas 5 are cross-linked and forming a structural layer of the final filter, and the unexposed areas 6 will be removed by solvent, at this step or at a later step of the process, such as the step shown in ( Figure 3, h.1 and h.2).
  • the main purpose of using a second layer on top of the first layer is to reduce the pore size according to the desired application (i.e. up to hundreds of nanometer).
  • the desired application i.e. up to hundreds of nanometer.
  • the top layer is overexposed and tends to be wider than the bottom layer which is relatively underexposed, resulting in pore closure.
  • proposed herein is a novel solution to make large holes ( ⁇ 10 ⁇ ) in the first layer and then reduce the pore size by laying parallel strips in the middle of the pores.
  • a second layer of SU- 8 2010 7 was spin-coated on top of the first layer ( Figure 3, d.1 and d.2).
  • quartz/chrome mask 8 with array of strips features was used to transfer the pattern precisely in the middle of the previous features 6.
  • the thickness of strips (parameter a in Figure 2) used for the present invention can be variable based on the desired application.
  • Alignment of the second mask 8 with patterns on the first layer 3 was carried out using precise microscopes of Karl Suss MA6 mask aligner. After exposing the second layer, wafer 1 was kept again on the hotplate at 95 °C for post exposure and cooled down to the room temperature for relaxation purpose for 10 minutes.
  • the sieving layer (layer one and two together) can be made from dry photoresists (i.e. overlay together using lamination) using lithography or stamping. There is also a possibility to make these layers (i.e. one or both of them) with metal deposition using sputtering or electroplating techniques.
  • one or more of the following patterning techniques can also be used: hot embossing, micro- and nano- molding and casting, electron beam lithography, nano imprinting, pattern transfer by stamping, interferometry lithography, x-ray or proton lithography, inkjet pattern deposition, micelle and other self-assembly of particles and molecules, amplification of electrohydrodynamic instabilities [Chou SY, et al, J Vac Sci Tehcnology, B 1999; 17:3197], micro or nano templates such as anodized porous alumina sheets, etc.
  • the filter pore may have various shapes which can be either a pore opening of low aspect-ratio, as shown in Figure 12(a), in which the dimension of the opening in all directions are nearly the same, or a pore opening of high aspect- ratio, as shown in Figure 12(b), in which the dimension of the opening in all directions are significantly different.
  • the particles may have various shapes having either low-aspect-ratio, as shown in Figure 13(a), in which the dimension of the particles in all directions are nearly the same, or shapes of high-aspect-ratio, as shown in Figure 13(b), in which the dimension of the particles in all directions are different significantly.
  • the filter pore shape should be designed to suit the shape of the particle of interest.
  • Figure 14 shows a few examples of choosing suitable shapes of pore openings for given particles of certain shapes.
  • the opening size which is designed to suit the size and shape of the particles of interest can be in the range of 10nm-5mm which can be the smallest size of the opening or the largest size of the opening.
  • the membrane support 14 can be made by anisotropic etching of Si wafer using KOH like the process in reference [7].
  • a double- sided polished silicon wafer in which we have made the sieving layer 5, 9 (i.e. both layers together) on one side and back-side etching of the Si wafer 1 from other side using KOH. In this case, it is not required to release the membrane from the Si substrate 1.
  • DRIE deep reactive ion etching
  • the most important impediment in fabrication of the polymeric micro/nano-filter with this method is the release of the multilayer micro-fabricated membrane 6 from the substrate 1 without membrane failure.
  • Backside support 14 helps the membrane to stay flat upon release from the substrate 1 , but high thickness of the support structure 14 will cause the entire structure to collapse and adhere to the substrate when the sacrificial layer starts to dissolve in the solvent. Therefore, finding a suitable material to be used as a sacrificial layer 2 for the releasing step is an important issue.
  • some methods have been proposed for this purpose, like sputtering (or electroplating) copper [12] or chromium [13] as a sacrificial layer 2 beneath the SU-8 film 3 and etching the metal film in the final step.
  • metals like copper or chromium will cause the imposition of extra steps like sputtering and also use of toxic material as an etchant for sacrificial layer removal.
  • appropriate polymers and solvents for release purpose may be employed. Table 1 shows some materials that were used as a sacrificial layer 2 in this study. All the solvents have no effect on the cured SU-8 film.
  • Table 1 Materials and process conditions that have been used for the release of micro/nano-filter from the substrate.
  • Figure 4 shows an SEM image of a multilayer polymeric membrane with the slotted pores and square-shape back support.
  • the optical image of the membrane ( Figure 5) shows the membrane structure clearly. It can be seen that the second layer is perfectly placed in the middle of the first layer and the pore size is reduced. The final pore size 1 5 of the membrane was 3x 12 ⁇ .
  • Figure 6 depicts the back-side view of a multilayer micro-sieve. This picture reveals that the obtained membrane has a smooth surface and high porosity, which make it ideal for microfiltration of biological samples like blood cells or isolation of microorganisms such as C. parvum oocysts. It should be noted that the support's openings must be large enough so as to not contribute any significant effect to the total hydraulic resistance to flow across the membranes U).
  • the pore density of the polymeric micro- fabricated membrane is much higher than the commercial filter like polymeric track-etched membrane with CV and average pore density of around 20% and 1 07 pores/cm 2 , respectively.
  • the histogram of the analyzed samples is depicted schematically in Figure 7.
  • FIG. 10 shows a part of the polymeric micro-sieve after filtration of C .parvum oocysts. The trapped oocysts 17 can be seen on the surface of the membrane.
  • the multilayer micro-sieve was back-flushed with an appropriate buffer (i.e. 1 % sodium polyphosphate (NaPP) and 0.1 % Tween 80) to recover the oocysts from the surface.
  • an appropriate buffer i.e. 1 % sodium polyphosphate (NaPP) and 0.1 % Tween 80
  • the back-flush was carried out using the peristaltic pump under 0.2 bar pressure for 2 minutes.
  • the following optical observations of the filter membrane showed that more than 90 ⁇ 5 % of C .parvum oocysts were recovered.
  • Unique features of the multilayer polymeric micro-sieve like the smooth surface and uniform pore-size greatly reduce the oocyst adhesion to the filter surface and enable us to achieve a very high recovery rate in comparison to the commercially available filters for this purpose.
  • Filtration throughput - Figure 1 1 illustrates the filtrate collection volume data of the micro-fabricated multilayer membrane and a track-etched polycarbonate membrane (Millipore, pore size of 3 ⁇ , Cat No: TSTP02500) under a constant pressure condition using tap-water.
  • the operating pressure was 0.5 bar and the turbidity was around 0.4 NTU.
  • the thickness of both membranes was 20 ⁇ .
  • a pressurized container was used to generate constant pressure filtration data. Permeate was collected in a container located on an electronic scale. The results indicate that the micro-fabricated polymeric filter has a higher throughput in comparison to the track-etched membrane for the same purpose (i.e. five times more). This can be attributed to the higher porosity and slit shape openings of the multilayer membrane. Experiments were performed in triplicate and presented results are the average of the measurements.
  • micro-fabricated multilayer filter Since micro-fabricated multilayer filter has unique properties like high porosity, smooth surface and biocompatibility, it can be used for a variety of applications like filtration of the white blood cells (leukocytes) from blood-cell concentration, cell culture, yeast filtration, detection of microorganisms and air monitoring.
  • white blood cells leukocytes
  • Biosensors as a barrier offering controlled diffusion for biological reagents and electrochemical detectors.
  • Diagnostic assays for flow control, sample preparation, blood separation (i.e. separation of CTC's from other blood cells or separation of WBC from RBC), and capture of latex microparticles. They can be used also for in vitro applications including diagnosis and protein separation.
  • Hemodialysis removing waste products such as creatinine and urea, as well as free water from the blood when the kidneys are in renal failure.
  • AOX Absorbable organic halides
  • Air monitoring Trace elements (chemicals, radioactivity) and particulate analysis (dust, pollens, and airborne particles).
  • Microorganism analysis Direct total microbial count, harvesting, concentration, fractionation, yeast, molds, Giardia, Legionella, coliform, and canine microfilaria.
  • Transparent micro-fabricated or track etched membrane filters provide a new tool for studying planktonic organisms. These ultra-thin transparent membranes are strong yet flexible, allowing for planktonic samples to be filtered and the membranes to be mounted directly onto microscope slides.

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Manufacturing & Machinery (AREA)
  • Inorganic Chemistry (AREA)
  • Textile Engineering (AREA)
  • Separation Using Semi-Permeable Membranes (AREA)

Abstract

L'invention concerne un filtre multicouche. Le filtre comporte au moins une première couche comportant une pluralité d'ouvertures et au moins une seconde couche perméable recouvrant la première couche et réduisant la taille des ouvertures. Le filtre peut par ailleurs comporter une ou plusieurs couches successives recouvrant la seconde couche, chaque couche réduisant par ailleurs successivement la taille des ouvertures. Le filtre peut être utilisé à des fins de séparation des particules dans un fluide ou un gaz. L'invention concerne aussi un procédé de fabrication d'un filtre multicouche.
PCT/SG2012/000343 2011-09-21 2012-09-20 Filtre multicouche WO2013043124A1 (fr)

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US14/346,392 US9327217B2 (en) 2011-09-21 2012-09-20 Multilayer filter

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SG201106927-5 2011-09-21
SG2011069275 2011-09-21

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WO2013043124A1 true WO2013043124A1 (fr) 2013-03-28

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WO2014128073A1 (fr) * 2013-02-25 2014-08-28 Siemens Aktiengesellschaft Procédé de fabrication d'un microtamis
US20220170913A1 (en) * 2013-09-25 2022-06-02 Arkray, Inc. Method for Processing Blood Sample
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JP2016010761A (ja) * 2014-06-27 2016-01-21 東京応化工業株式会社 メンブレンフィルター
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JP2016010762A (ja) * 2014-06-27 2016-01-21 東京応化工業株式会社 メンブレンフィルターの製造方法
KR102361841B1 (ko) * 2014-06-27 2022-02-11 도쿄 오카 고교 가부시키가이샤 멤브레인 필터
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US20160279898A1 (en) * 2015-03-26 2016-09-29 Tokyo Ohka Kogyo Co., Ltd. Laminated film
US10137665B2 (en) 2016-01-14 2018-11-27 Tokyo Ohka Kogyo Co., Ltd. Method for manufacturing laminate, and laminate
TWI708684B (zh) * 2016-01-14 2020-11-01 日商東京應化工業股份有限公司 積層體之製造方法、及積層體
EP3415216A1 (fr) * 2017-06-13 2018-12-19 BSH Hausgeräte GmbH Élément filtrant pour hotte aspirante
WO2019061540A1 (fr) * 2017-09-30 2019-04-04 王爱娟 Générateur d'eau riche en hydrogène
WO2022122389A1 (fr) * 2020-12-08 2022-06-16 Global Life Sciences Solutions Operations Uk Limited Membrane polymère poreuse ayant un anneau anti-déchirure
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WO2023046908A1 (fr) * 2021-09-24 2023-03-30 Pluriselect Life Science Ug (Haftungsb.) & Co.Kg Dispositif comprenant une couche présentant des pores pourvue d'une surface fonctionnelle microstructurée

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